So the intrepid couple set up a Pozible fund, hoping to raise $15,000 to go back to the tropics and see how the roos are faring, ten years down the track.

"This government is not particularly in support of science, but this is too important and we're not going to take no for an answer. So we decided to take matters into our own hands and head back there."

Only two days after launching their campaign, they got an email from Pozible. Someone had donated over $2 billion. They couldn't believe it, but it was right there on the page.

Jen and Euan say they have no idea who Jeffrey Green is. The mystery benefactor even claimed a prize worth $2000, which is more than had been donated to the whole campaign at that point.

A spokesperson for Pozible says they rejected the pledge because it was deemed suspicious.

"When we called it was a wrong number, which was a fairly clear indication to us that it wasn't a genuine pledge. We could also see that the person had tried to pledge twice with different payment options, but the same amount each time. They were pretty determined," the spokesperson told BuzzFeed News.

Pozible has since removed Jeffrey Green's account.

"That said, $2 billion is probably the most amount of money that's ever been pledged to a crowdfunding campaign ever, and we're a little sad we couldn't be part of making history!"

Jen and Euan say they have no idea why someone pulled this prank on them.

Jen Martin

"It would cost $400 million to save all of Australia's threatened species, Jen says.

"You just can't help but dream that if there were philanthropists out there, people who could see that was important, what we could do with that money

We're losing an iconic species without people noticing and that's very sad, especially when it is something as big and gorgeous as a kangaroo."

But they're determined not to let that stop them, and are already a third of the way to their $15,000 goal.

Jen Martin

It's not $2 billion, but it'll be enough to get their roo-mobile back on the road again.